天然沉积粘性土结构性压缩模型研究

项目名称： 天然沉积粘性土结构性压缩模型研究

项目编号： No.50878050

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 轻工业、手工业

项目作者： 洪振舜

作者单位： 东南大学

项目金额： 36万元

中文摘要： 本项目得出了以下三方面的主要研究成果：1）基于Burland的固有压缩概念和Desai的扰动状态概念，结合天然沉积土原状样和重塑样的压缩曲线特征，提出了能够考虑初始含水率影响的天然沉积土原状样取样扰动的定量评价方法，建立了压缩变形参数与扰动度之间的定量变化规律；2）明确了天然沉积土固结屈服应力和压缩指数与不同应力路径的应力比之间的关系，分析了天然沉积土的静止土压力系数在压缩过程中的变化规律，探讨了应力路径对天然沉积土屈服面和应力应变曲线的影响；3）基于扰动状态概念建立了可以定量描述天然沉积软粘土压缩曲线的数学表达式，提出了天然沉积软粘土的双对数线性化压缩模型，基于Burland的固有压缩概念和本研究提出的考虑天然沉积土初始沉积状态的扰动评价方法和变形参数修正方法，提出结构性参数比反映天然沉积软粘土结构性丧失的过程，参照Liu & Carter基于扰动状态概念提出的一维结构性压缩模型和前人构建正常屈服面/结构屈服面二应力边界面模型的思路，考虑硬化规则中塑性体积变形和剪切变形的共同影响，建立了一个考虑各向异性和试样扰动影响的天然沉积粘性土结构性弹塑性压缩模型。

中文关键词： 土结构性；压缩模型；天然沉积粘性土；各向异性；扰动程度

英文摘要： The main results obtained in this study were summarized as follows: 1) A simple index assessing the extent of sample disturbance is proposed in this study with considering effect of initial water content using the intrinsic concept proposed by Burland and the disturbed state concept proposed by Desai. The degree of sample disturbance is defined as the ratio of the difference between the in-situ void index and the void index of the undisturbed sample tested in the laboratory to the difference between the in-situ void index and the void index of the completely-remolded clay having the initial water content equal to the natural water content. All these indices are determined at the same effective overburden stress. In addition, a simple method is proposed in this paper to correct the mechanical parameters measured in laboratory considering the degree of sample disturbance; 2) The change law in compression behavior with the different stress paths was investigated. The mean yield effective stress and compression index increases with the increase in stress ratio to a maximum and then decrease with the increase in stress ratio. The comparison in yield behavior between consolidated undrained triaxial compression tests and one-dimensional compression test indicated that the coefficient of earth pressure at rest increases with stress level during the yielding of compression, and becomes constant when the stress level is in the post-yield state; 3) A new structure index is prosped to describe the loss of soil structure during compression for natural clays using the disturbed state concept, in which the compression curve is expressed in the bilogarithmic plot. Following the clue of current method in establishing the modified cam-clay model and the double-inclined-yielding-surface elasto-plastic constitutive model, a new structured compressive model for natural clays is established with considering the effects of anisotropy and sample disturbance, using the disturbance state concept proposed by Desai, the intrinsic compressive concept proposed by Burland, 1-D structured compressive model proposed by Liu & Carter, as well as the quantitative evaluation method of sample disturbance and corrected method of deformation parameters proposed in this study.

英文关键词： soil structure; compression model; natural clay; anisotropy; sample disturbance